XomeDx® Slice – Epidermolysis Bullosa (EB)

Casandra

Casandra Test Code GE87923Version 1 (DRAFT)

Performing Lab

Lab GeneDxLab Test ID 707

XomeDx® Slice – Epidermolysis Bullosa (EB)

Clinical Use

Use

Epidermolysis bullosa (EB) is an inherited skin and connective tissue disease characterized by skin fragility and blister formation with mild trauma. Different inheritance patterns occur: autosomal dominant forms (e.g., EBS involving KRT5, KRT14) and autosomal recessive forms (e.g., EXPH5, TGM5, FERMT1). Dystrophic EB (DEB) involves COL7A1 with dominant or recessive inheritance and often causes scarring. Junctional EB (JEB) involves several genes like COL17A1, LAMA3, LAMB3, LAMC2, ITGA6, ITGB4 with variable severity. Variant forms with phenotypes such as EB with pyloric atresia (ITGA6, ITGB4, PLEC) or EB‑MD (PLEC) exist. Peeling skin syndromes (PSS) involving genes such as CDSN, TGM5 (acral PSS), CHST8, CSTA, SERPINB8, FLG2 may complicate interpretation and may require immunofluorescence studies for clarification. The test helps establish a molecular diagnosis in individuals with clinical or suspected EB, guiding inheritance risk and subtype classification.

Special Instructions

This test is a “Slice” option (custom slice) available when a prior XomeDx® (full exome) has been performed. It corresponds to test code 707 on the GeneDx test requisition form under Custom Slice testing options. Family member specimens may be included per ordering instructions (e.g., for trio or duo analysis). Clinical documentation (e.g., clinic notes, pedigree, consent) must be submitted for exome‑based Slice orders in accordance with GeneDx requirements. Refer to requisition form for family sample handling.

Limitations

Next‑generation sequencing with CNV calling is used to detect sequence variants and most deletions/duplications involving three or more coding exons. Smaller deletions or duplications may not be reliably identified, and loss‑of‑function variants only are reported in FLG2. Reported clinically significant variants are confirmed by an orthogonal method. Interpretation may be complicated in variant phenotypes and may require adjunct immunofluorescence testing.

Test Details